1. Field of the Invention
The present invention relates to a protecting system for an engine equipped with an electronically controlled fuel injection apparatus. More particularly, the present invention relates to a system for protecting an engine by preventing occurrence of an abnormal revolution such as an overrun at abnormal reduction of a battery voltage caused, for example, by a trouble in a charging system of a battery.
2. Description of the Related Art
As the 2-cycle engine for a two-wheeled vehicle or a snow mobile, there has been adopted an engine having a fuel supply system where injection of a fuel is electronically controlled by using a fuel injection valve (see, for example, Japanese Unexamined Patent Publication No. 63-255543). For example, there can be a fuel supply system in which a fuel injection valve is arranged in an intake manifold zone of each cylinder, and injection is simultaneously effected in all of the cylinders.
In a two-wheeled vehicle having an electronically controlled fuel injection system, when the voltage is abnormally reduced because of the trouble in a charging system of a battery or the like, the electronically controlled fuel injection apparatus is operated for a while by the voltage of the battery, however, if the voltage is gradually reduced and becomes lower than the rated voltage of a control unit, there is a possibility that an abnormal operation in the fuel injection apparatus will occur causing an abnormal engine state, as for example, an overrun of the engine.